So I always knew that you need to keep your probiotics in the fridge. What I did not know is that not all companies guarantee that thier product is alive at exiration. Meaning that if at some point in the delivery process or packaging process they are left to get warm, then thats it they are dead. Now why would someone sell dead probiotics is what you’re thinking?. Well its not bad for you to them, they will feed the “good” bugs you already have and keep them going. Provided you have any left. If you need to REPLENISH your good flora you need to read the package for this guarantee. This has been my problem I think. Because I have been taking 2 at 3.4 billion a piece for weeks with no improvment and mine were left out during a move and got warm.